<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            padding: 0;
            margin: 0;
            list-style: none;
        }

        ul>li {
            background-color: #0f0;
            margin: 10px;
        }

        ul>.two+li {
            background-color: #00f;
        }

        .box>div {
            width: 200px;
            height: 200px;
            background-color: #0f0;
            font-size: 20px;
            color: #fff;
        }

        .box>div::before {
            content: "22";
            display: inline;
            width: 50px;
            height: 30px;
            background-color: #ccc;
        }

        .box>div::after {
            content: "33";
            display: block;
            width: 50px;
            height: 30px;
            background-color: #ccc;
        }

        .box2 {
            background-color: #ccc;
            /* height: 50px; */
            /* overflow: hidden; */
        }

        .box2::after {
            content: "";
            display: block;
            clear: both;
            overflow: hidden;
        }

        .box2>div {
            width: 50px;
            height: 50px;
            background-color: #0f0;
            margin: 10px;
            float: left;
        }

        .mi {
            width: 150px;
            height: 100px;
            display: flex;
            flex-wrap: wrap;
        }

        .mi>div {
            width: 50px;
            height: 50px;
            background-color: #000;
            font-size: 20px;
            color: #fff;
            text-align: center;
            line-height: 50px;
            position: relative;
        }

        .mi>div::after {
            content: "";
            display: block;
            width: 42px;
            height: 1px;
            background-color: #ccc;
            position: absolute;
            bottom: 2px;
            left: 4px;
        }

        .mi>div::before {
            content: "";
            display: block;
            width: 1px;
            height: 42px;
            background-color: #ccc;
            position: absolute;
            bottom: 4px;
            left: 2px;
        }

        .box>p::first-letter {
            font-size: 50px;
            background-color: #0f0;
            color: #ccc;
        }

        .box3>div {
            width: 100px;
            height: 100px;
            background-color: #0f0;
        }

        .box3>div:nth-of-type(even) {
            background-color: #00f;
        }

        .box3>div:first-of-type {
            background-color: aqua;
        }

        .box3>p:nth-child(2) {
            background-color: #000;
        }
    </style>
</head>

<body>
    <ul>
        <li>11</li>
        <li class="two">22</li>
        <li>33</li>
        <li>44</li>
        <li>55</li>
        <div>77</div>
    </ul>

    <div class="box">
        <div>
            11</div>
        <p>22</p>
        <p>33</p>
    </div>

    <div class="box2">
        <div>11</div>
        <div>22</div>
        <div>33</div>
        <div>44</div>
        <div>55</div>
        <!-- <p style="clear: both;"></p> -->
    </div>

    <div class="mi">
        <div>11</div>
        <div>22</div>
        <div>33</div>
        <div>44</div>
        <div>55</div>
        <div>66</div>
    </div>

    <div class="box3">
        <div>11</div>
        <p>11</p>
        <div>22</div>
        <p>22</p>
        <div>33</div>
        <p>33</p>
        <div>44</div>
        <div>55</div>
    </div>

    <div style="height: 200px;"></div>

</body>

</html>